Nutritional supplements can improve colour vision, contrast sensitivity and other measures of visual functioning in people with diabetes -- with or without retinopathy, researchers say.
The nutrients could offer a new line of defense against diabetic retinopathy, said the researchers from four US states. They published the findings from the Diabetes Visual Function Supplement Study (DiVFuSS) June 2015, in the British Journal of Ophthalmology.
While pharmaceuticals and photocoagulation can often successfully treat diabetic retinopathy, they don’t work adequately in many patients. At the same time, the Age-Related Eye Disease Study (AREDS) demonstrated that a nutritional supplement could slow the progress of age-related macular degeneration. This led the researchers to wonder whether supplements might prevent or treat diabetic retinopathy. So investigators gave 39 patients a formulation of micronutrients that had previously shown effects related to vision or the etiology of diabetes (EyePromiseDVS, Zea Vison, St. Louis, Missouri.)
The formula consisted of vitamins C, D3 and E (d-a tocopherol), zinc oxide, eicosapentaenoic acid, docosahexaenoic acid, a-lipoic acid (racemic mixture), coenzyme Q10, mixed tocotrienols/tocopherols, zeaxanthin, lutein, benfotiamine, N-acetyl cysteine, grape seed extract, resveratrol, turmeric root extract, green tea leaf, and Pycnogenol (patented French Maritime Pine Bark extract, sp Pinus pinaster, Horphag Research, Geneva, Switzerland).
In animal trials, the formula had attenuated diabetes-induced metabolic abnormalities in the retina, including oxidative stress, mitochondrial damage and upgregulation of inflammatory mediators, the researchers said. And it prevented the formation of degenerative capillaries in the retinal microvasculature.
Twenty-seven of the patients in DiVFuSS had type 1 diabetes, and 40 had type 2 diabetes.
Fifteen had mild to moderate diabetic retinopathy, and 24 had no diabetic retinopathy. All patients took two gel capsules per day. The 15 with mild to moderate retinopathy took two capsules of the supplements. The 24 without diabetic retinopathy took one capsule of the supplement and one capsule of an identical-looking placebo. Another 28 patients took the placebo alone. In this group, 11 had type 1 diabetes and 17 had type 2 diabetes. Fifteen had retinopathy and 13 did not.